Postfix can't talk to Gmail
I'm running a mail server off a local machine using Postfix for a myself and a site me and a mate are starting. Everything works but one person wants their account forwarded to their Gmail account so that's all set up but Postfix keeps throwing up errors because it can't connect to Gmail on port 25.
The help in Gmail seems to say that port 25 should work but if it doesn't (ISP restrictions however I can access other mail servers on port 25) then 465 and 587 are also available. Is there a way I can make Postfix try one of those ports instead?